Dormouse: European protected species (SIN005)

Biology and distribution

Location

The common dormouse is one of our most recognisable small rodents because of its golden fur, furry tail and large black eyes. It is about the same size as other mice (weight 17-20g, but up to 30-40g just before hibernation), but has a rather different lifestyle. The dormouse now has a restricted distribution in Britain, with few sites north of the Midlands (except where it has been reintroduced). See Figure 1 below.

Figure 1 

Habitat

The dormouse is a nocturnal animal that lives mainly, though not exclusively, in deciduous woodland and scrub, where it feeds among the branches of trees and shrubs. Except for hibernation, it rarely descends to the ground and is reluctant to cross open spaces, perhaps because of the danger of predation.

It feeds on a wide variety of arboreal foods, including flowers (nectar and pollen), fruits (berries and nuts) and some insects (especially aphids and caterpillars). It will also eat buds and young leaves, but not mature leaves. A high degree of diversity among tree and shrub species is desirable in order to ensure that an unbroken sequence of foods is available throughout the summer. Certain tree species are particularly valuable as providers of food at different times of year. Hazel appears to be an important provider of insects, and its nuts form the main food used to fatten up for hibernation. Where hazel is scarce or absent smaller fruit seeds, such as those from hornbeam or blackthorn sloes may suffice, but offer less food in exchange for the gnawing needed to open them.

Although woodland is the most important habitat for dormice, they will also live in hedgerows, preferring species-rich hedgerows that are interconnected or connected to woodland. The best hedgerows for dormice are wide and tall with abundant mast and fruit-bearing trees and shrubs.

Lifecycle

In autumn, usually early October, dormice hibernate in nests built just beneath the surface of the ground, often under moss or leaf litter. They remain in these nests until spring (late April or early May), surviving on fat laid down the previous autumn. During summer, dormice build nests in tree cavities or in shrubs. Nests are usually woven from shredded honeysuckle bark or, if this is not available, grasses or leaves.

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